Flow: Regression: `hidden` attribute is set to false when server instantiates the component

[manolo]

Having this code, the button is finally shown (hidden attribute is removed)

<vaadin-button id="foo" hidden>Foo</vaadin-button>

@Id("foo")
private Button foo;

[ZheSun88]

a short investigation with platform 10.0.0.alpha14.

the hidden attribute can be only set via using button.setVisible(true/false) api, but if we set the attribute from the template file with <vaadin-button id="foo" hidden>Foo</vaadin-button> or <vaadin-button id="foo" hidden="true">Foo</vaadin-button>, the attribute will be removed, when server instantiates the component.

for setting other attribute from template file, it works as expected. (tested with disabled).

[denis-anisimov]

Why does it remove the attribute when the server instantiates the component?
That's the question.

[denis-anisimov]

I know the reason. Let it be assigned to me to avoid wasting time from someone who doesn't familiar with the situation.